Self-healing materials with conductive properties have attracted growing interest in both academia and industry due to their potential applications in a broad range of technologies, such as self-healing electronics, medical devices, artificial skins, and soft robotics. For practical applications, these materials should demonstrate good conductivity and repeatable mechanical and electrical self-healing properties at room temperature, as well as decent mechanical strength and flexibility, to meet the requirements for fabrication of flexible devices.
Great efforts have been dedicated to developing conductive self-healing materials. Researchers have developed the use of microcapsules containing liquid precursor healing agents for structural healing. In these systems, the local healing agent is depleted after capsule rupture. Others have demonstrated an alternative approach by combining a supramolecular organic polymer and nickel microparticles, resulting in a composite with mechanical and electrical self-healing properties at ambient conditions; whereas a large number of inorganic particles are needed for the preparation of composite. Recently, a conductive and self-healing hydrogel has been synthesized by polymerization of pyrrole within agarose matrix. The self-healing behavior of the resultant composite, however, can only be excited under external thermal or optical stimuli. Therefore, the development of self-healing, highly conductive, mechanically strong, and light-weight materials remains a critical challenge.
In the past decades, the supramolecular chemistry has witnessed rapid development of metallo-supramolecular structures based on the highly directional and predictable feature of metal-mediated self-assembly. Driven by directional and conjugated structures and intermolecular forces, these supramolecular structures could further hierarchically self-assemble into higher order nanostructures, i.e., supramolecular gels. More importantly, due to the moderate bond energy of metal-ligand bonds and non-covalent interactions among supramolecules, the supramolecular gels can dynamically assemble or disassemble, associate or dissociate at room temperature, thus showing features such as self-healing property and sol-gel phase transitions. Recently, conductive polymer hydrogels (CPHs) such as polyaniline (PANI) and polypyrrole (PPy) hydrogels have been synthesized using phytic acid as the gelator and dopant. The framework of the resulted CPHs provides ideal 3D interconnected paths for electron transport, thus reaching a conductivity as high as 11 S/m. Such 3D hierarchically porous structures offer large open channels to support the introduction of second gel component and provide an ideal interface between conductive hydrogels and other synthetic systems. However, the fragile nature and lack of self-healing property inhibits CPHs' further applications.
There is a need for conductive materials exhibiting self-healing behavior. There is a need for materials with good conductivity, repeatable mechanical and electrical self-healing properties at room temperature, and good mechanical strength and flexibility. There is a further need for a method providing a variety of networks using a common synthetic strategy.
The invention disclosed herein addresses, in part, one or more of the aforementioned needs.